After 40 minutes into a race, Vaidev has run ⁵₁₁ of the route while Oscar has covered only ²₁₁ of the distance. Vaidev runs at the same average speed throughout the race and Oscar’s average speed is 108 m/min slower than Vaidev’s. If Oscar wants to finish the race at the same time as Vaidev, by how many percent should he increase his average speed by for the remaining part of the race? Round off your answer to the nearest whole number.
Extra distance that Vaidev ran more than Oscar in first 40 min
= 40 x 108
= 4320 m

Fraction of the entire distance that was covered by Vaidev more than Oscar in the first 40 min
= ⁵₁₁ - ²₁₁
= ³₁₁

³₁₁ of the entire distance = 4320 m
¹₁₁ of the entire distance = 4320 ÷ 3 = 1440 m

Distance that Oscar ran in the first 40 min
= 2 x 1440
= 2880 m

Oscar's average speed
= 2880 ÷ 40
= 72 m/min

Vaidev's average speed
= 72 + 108
= 180 m/min

Fraction of the journey that Vaidev needed to run to complete the race
= 1 - ⁵₁₁
= ⁶₁₁

¹₁₁ of the entire distance = 1440 m
⁶₁₁ of the entire distance = 6 x 1440 = 8640 m

Duration that Vaidev would take to complete
= 8640 ÷ 180
= 48 min

Fraction of the journey that Vaidev needed to run to complete the race
= 1 - ²₁₁
= ⁹₁₁

⁹₁₁ of the entire distance = 9 x 1440 = 12960 m  

Speed that Oscar needs to take to complete distance at the same time as Vaidev
= 12960 ÷ 48
= 270 m/min

Increase in Oscar's average speed
= 270 - 72
= 198 m/min

Percentage increase in Oscar's average speed
= ¹⁹⁸₇₂ x 100%
≈ 275%

Answer(s): 275%